Spin-actuated apparatus



8- 1968 E. N. GERICK 3,397,641

SPIN-ACTUATED APPARATUS Filed June 12, 1967 d INVENTOR.

W g '8 3,3 Ed NGerick 55m HHV BY 2? United States Patent 3,397,641 SPIN-ACTUATED APPARATUS Edwin Nathan Gerick, Phoenix, Ariz., assignor to Motorola, Inc., Franklin Park, III., a corporation of Illinois Filed June 12, 1967, Ser. No. 645,453 8 Claims. (Cl. 102-79) ABSTRACT OF THE DISCLOSURE Spin actuated apparatus having a base plate with a spin axis and two weights radially movably disposed on one diameter of the base plate. A rotor cammingly engages the weights and yieldably urges the weights radially inward. As the base plate spins on the spin axis, the weights are urged radially outward by centrifugal force and thereby rotating the rotor against the yieldable urging. Such rotation moves the rotor from a safe or deactivated position to a second rotational position which is an armed or activated position.

Background of the invention This invention relates to spin actuated apparatus especially of the type that may be used for arming explosive shells while guaranteeing against premature activation.

Prior safe and arm mechanisms include clock-type arming devices which are activated after the shell or missile has been fired or launched. Other forms of arming devices include impact and acceleration actuated devices.

It is known that shells and missiles have a tendency to spin about a certain axis. To that end, some safe and arm mechanisms have been designed to be spin actuated. Such devices include those wherein weights move radially outward upon the onset of the shell or missile being spun on its own axis such as to change the moment of inertia of the rotor with respect to the shell and thereby causing relative rotational motion which arms the device. Yet other spin actuated devices are quite complex and therefore subject to malfunctions. It is desirable, therefore, to have a simple reliably operating device with few moving parts.

Summary of the invention It is the object of the present invention to provide a simple spin actuated apparatus.

It is another object of this invention to provide a spin actuated apparatus having a high threshold of activation and a long rotational motion to provide a long travel between deactivated and activated positions.

Apparatus embodying the teachings of the present invention include the features of a pair of weights radially movable with respect to a spin axis. The weights are cammingly engaged with a rotor such that upon the apparatus beginning to spin urge the rotor to rotate in a first sense, usually toward an activated condition. The rotor is yieldably urged in the opposite rotational sense forcing the weights radially inward, usually in a deactivated condition. All parts are preferably balanced with respect to the spin axis.

The drawing FIG. 1 is an enlarged exploded perspective view of an apparatus embodying the teachings of the present invention as may be used in an explosive shell.

FIG. 2 is an enlarged plan view of the FIG. 1 apparatus in an unarmed or deactivated condition with added phantom lines showing the positions of the various parts when deactivated.

FIGS. 3 and 4 are sectional views respectively taken in the direction of the arrows along lines 33 and 44 for ice showing the relationship of the parts of the FIG. 1 apparatus.

Description of the illustrative embodiment Referring now to the drawings, like parts and structural features are indicated by the same numerals in the various views. The spin actuated apparatus includes a base member or housing 10 shown in the shape of a cup, no limitation thereto being intended. Member 10 has base plate 11 with an upstanding boss 11A having central aperture 12 therein. Base plate 11, when inserted in a shell, is located such that the axis of aperture 12 is aligned with the spin axis of the explosive shell. Radially extending slots 13 and 14 are disposed on a common diameter with respect to aperture 12 and are adapted to radially movably receive depending guides 15 and 16, respectively, of the weights 17 and 18. When the device is in an unarmed or deactivated condition, weights 17 and 18 are normally engaging boss 11A. As member 10 is rotated with the shell, weights 17 and 18 are centrifugally urged to move radially outwardly along guide slots 13 and 14, respectively. This radial movement is used to cam rotor 19 to rotate in the direction of the arrow 20 from an initial deactivated to an activated condition, as will be described.

The camming engagements between weights 17, 18 and rotor 19 are provided by upstanding members or cams 21 and 22, respectively, on the weights which are movably inserted in apertures 23 and 24, respectively, in rotor 19. Apertures 23 and 24 are disposed on a common axis about central aperture 25. Aperture 25 is aligned with aperture 12 when assembled for receiver retaining pin 26 which is press fit into aperture 12 of member 10. Rotor 19 is free to rotate about ret aining pin 26. It is seen that as the weights 17 and 18 move radially outward through the action of member 10 spinning about the aperture 12 axis, cams 21 and 22 act on rotor 19 causing it to rotate in the direction of arrow 20.

The rotor 19 is kept in an unarmed or deactivated condition by spring 27 yieldably urging rotor 19 in a rotational sense opposite to that indicated by arrow 20. Inner end portion 28 of spring 27 is disposed in the kerf in the head of retaining pin 26 while the outer end portion 29 is inserted in radial slot 30 of rotor 19. Spring 27 is positioned such that it yieldably urges rotor 19 to rotate counterclockwise as shown in FIG. 1. This counterclockwise urging moves weights 17 and 18 radially inward until they engage boss 11A as best seen in FIG. 2.

When the described illustrative embodiment is used as a safe and arm mechanism for an explosive shell, for example, a pair of bosses 31 and 32 are formed on rotor 19 on one diameter for rotationally balancing the apparatus. Boss 31, when rotated as above-described by the spinning of member 10, moves from an unarmed or deactivated position, indicated generally by numeral 34, toward activation aperture 33 formed in base plate 11. Boss 31 is formed with a detonator receiving cavity 34A, as best seen in FIG. 3, and is designed such that the detonator and boss 31 have exactly the same weight as boss 32. When boss 31 is in position 34, the detonator is not accessible to outside member 10. However, when the spin of member 10' causes weights 17 and 18 to move radially outward for urging rotor 19 to rotate in the direction of arrow 20, detonator cavity 34A is then positioned over aperture 33 giving access to the detonator by an actuator (not shown) of usual design. The latter is in an armed or activated condition.

The selection of weights 17 and 18 and the strength of spring 27 are such that a high threshold is provided for the spin actuation, as above described. When this threshold is reacted, rotor 19 is usually selected to rotate through an angle of about for providing a relatively long travel between the deactivated and activated conditions.

From inspection of the drawing, it is seen that the rotor 19 rotational movements may be limited by the cam pins 21 and 22 acting thereon through apertures 23 and 24. Such rotational limits correspond to given innermost and outermost movement, and vice verse, of weights 17 and 18. In the illustrated embodiment, the radial travel of weights 17 and 18 was selected to be less than the permitted rotation of rotor 19. It was believed that such limiting of motions within the apparatus would provide easier tolerances in mass producing this device. It may be noted that either the length of slots 13 and 14 or the radial spacing between boss 11A and the outer wall of member 11 may be used to limit the radial movements of weights 17 and 18. Also, a greater plurality of weights and corresponding slots and earns may be used, preferably symmetrically spaced about the spin axis for keeping the apparatus balanced.

I claim:

1. Spin actuated apparatus including in combination,

a spin-nable base member having a spin axis,

a plurality of weights radially movably disposed on said member,

a plurality of cam means respectively disposed on said weights symmetrically about said spin axis,

a rotor disposed on said member and rotatable about said spin axis with respect to said member and having a plurality of cam engaging means symmetrically disposed with respect to said spin axis in sliding operative engagement with said cam means, respectively,

said rotor and said base member forming an annular cavity therebetween and said weights movably retained by said rotor and said base member inside said cavity with the weights continuously movably engaging both said rotor and said base member,

means yieldably urging said rotor in a first rotational sense moving said weights to a radial inward position inside said cavity and said weights being urged radially outwardly in response to said member spinning about said axis for urging said rotor in a rotational sense opposite to said first rotational sense.

2. The apparatus of claim 1 wherein said cam engaging means are all identical one with the other and lie in a common circle about said spin axis.

3. The apparatus of claim 1 wherein said base member has an aperture coaxial with said spin axis and a retaining pin fixedly secured in said member aperture for movably retaining said weights and rotor with respect to said member.

4. The apparatus of claim 1 wherein said member has an upstanding boss about said spin axis and serving as a stop member for limiting inward radial movement of said weights.

5. The apparatus of claim 1 wherein said rotor has a plurality of bosses symmetrically disposed about said spin axis with one of said bosses having a detonator therein,

said rotor being balanced with respect to said spin axis irrespective of its rotational position,

and said member having an activation aperture with said one boss being rotatable to be aligned with said aperture for selectively exposing said detonator through said aperture in accordance with spin of said member.

6. The apparatus of claim 5 wherein said member has a central aperture coaxial with said spin axis,

a retaining pin fixedly secured to said member in said central aperture with said rotor being ro-tatably held by said pin,

a spring having one end portion stationarily secured to said rotor and a second end portion stationarily secured to said pin and continuously yieldably urging said rotor to rotate in a first sense for keeping said detonator away from said activation aperture.

7. The apparatus of claim 6 wherein said member is cup shaped with a base plate having a plurality of radially extending slots,

said weights having a depending radially elongated guide radially movably disposed in each of said slots, respectively.

8. The apparatus of claim 7 wherein said member limits the innermost and outermost radial movements of said weights corresponding to rotation of said rotor less than those extreme rotational positions permitted by said cam means operative engagement with said rotor and wherein said outermost movement corresponds to an activated condition with said detonator aligned with said activation aperture and said innermost movement corresponding to a deactivated condition.

References Cited UNITED STATES PATENTS 11/1925 Brayton 102-79 3/1967 Keller et al 10279 

